WASHINGTON — A federal audit as recently as January warned there was a “high risk” that the government’s information-sharing system would not prevent a terror attack, raising questions about whether a communications breakdown allowed the Boston Marathon bomb plot to evolve undetected and its perpetrators to elude quick capture.

The information issue arose again on Wednesday when US officials disclosed that the CIA had placed Tamerlan Tsarnaev on a terrorism watch list several months after the FBI had placed him on a different watch list. Both actions were based on separate alerts provided by Russian authorities, but they failed to help the United States recognize and intervene to head off the threat or identify Tsarnaev as a suspect once the bombs went off.

Also Wednesday, new details emerged about the capture of the younger Tsarnaev brother, Dzhokhar, after Tamerlan was killed in a gunfight with police.

Members of the MBTA SWAT team that arrested Dzhokhar Tsarnaev confirmed that, despite their fears, the 19-year-old bombing suspect did not appear to have a weapon when they finally pulled him from the bullet-riddled boat in a Watertown backyard where he was hiding. He was struggling to remain conscious, and had no weapon on him, they said.

“He looked like a bloodied-face suspect in need of medical care,” SWAT team member Kenny Tran said in an interview with the Globe.

Law enforcement agents said Wednesday they do not believe the wound on his neck was the result of a suicide attempt — contrary to some published reports.

SWAT team member Jeff Campbell said the 2-inch-long bleeding wound on the front of his neck looked more like a cut made by shrapnel from an explosion.

A second law enforcement official echoed the view that the wound did not appear to be self inflicted.

Also Wednesday, Representative Dutch Ruppersberger, a Maryland Democrat and the ranking member on the House Intelligence Committee, said the dual bombs near the Marathon finish line were detonated by a remote control for a toy car. Ruppersberger made his comments after a briefing by law enforcement officials.

In Russia, the news agency RIA Novosti reported Tsarnaev’s parents had agreed to come to the United States to answer questions.

Members of Congress, meanwhile, expressed alarm Wednesday that 12 years of efforts to improve the sharing of information – a federal priority since the Sept. 11 attacks — weren’t enough to track the international movements of bombing suspect Tamerlan Tsarnaev despite a string of suspicions about his actions.

Even though Tsarnaev was placed on two separate terror tracking lists in 2011, the FBI failed to detect his travel to the Dagestan region of Russia for six months in 2012 because his name was spelled wrong on an airline passenger list, according to officials. The Department of Homeland Security did detect his travel.

Senator Lindsey Graham, a South Carolina Republican, said he couldn’t fathom why the Department of Homeland Security apparently knew Tsarnaev was going to Russia, but the FBI did not.

“How could we not know that he was going to Russia, if it pinged at Homeland Security, why didn’t the FBI and other agencies know about it?” Graham said.

“Eleven, twelve years after 9/11, it can’t be such that when you are informed by a foreign government that the person — who actually committed the terrorist attack — may actually have been a terrorist in the making in 2011,” Graham said.

Problems with the government’s information sharing have been known in Washington circles, if not well-publicized. The Government Accountability Office, a federal unit that audits the efficiency of federal programs, reported in January that information sharing remained a “high risk” problem for the US government, the most deficient ranking that can be given in a GAO evaluation.

The “high risk” ranking was first given in 2005 and, despite what the GAO called improvement, enough serious questions remain that the program was again given that ranking in January. The audit has not been widely reported.

White House Press Secretary Jay Carney declined to say at a briefing whether President Obama was confident that federal databases on potential terrorists were working, or whether federal agencies were sharing enough information, or if information was properly followed up, saying those questions would be addressed in an investigation.

Obama “wants every agency involved in this to do a broad investigation into what happened, what we knew, what inspired and motivated these two individuals, and the steps that they took that led to the terrorist attacks in Boston a week ago Monday,” Carney said.

Members of Congress on Wednesday raised questions not only about whether there are gaps in information sharing between the FBI, CIA, and the Department of Homeland Security, but also about whether crucial data was provided to “Fusion Centers” that were set up after the Sept. 11, 2001 attacks to ensure that state and local officials are in the loop.

It was not clear Wednesday, for example, whether a Fusion Center in Massachusetts was given direct information that the FBI had received warnings from Russia about Tamerlan Tsarnaev.

The Commonwealth Fusion Center is located in Maynard, Mass., where a variety of local and state public safety agencies collect and analyze information about potential terrorist threats. The Massachusetts State Police did not respond to questions about whether the center was alerted to the FBI’s concerns about Tsarnaev. The FBI and Homeland Security also did not return calls about the matter.

“We’ve got lots of questions,” said Senator Saxby Chambliss, a Georgia Republican on the intelligence committee. “We’re still trying to figure out what we knew that either did or didn’t get shared in the right way and if we had a breakdown in our systems, where was it, so we can fix it? Frankly, I don’t know if there’s anything we’ve seen that might have prevented the incident from happening. But that question has not fully been answered either.”

Senator John McCain, an Arizona Republican, said he was “very, very concerned” about problems with information sharing.

“There were so many mistakes made . . .” he said. “I wouldn’t pick out the Fusion Center but obviously we need to review this whole situation. . . . How did he get out of the country with only the DHS knowing? They didn’t know when he came back. The FBI dropped him from the list, the whole lack of coordination and information . . . clearly a lack of coordination among agencies.”

Russia’s Federal Security Service warned the FBI about Tsarnaev in early 2011, saying he was a “follower of radical Islam and a strong believer’’ and was prepared to leave the United States to “join unspecified underground groups’’ in Dagestan, according to the FBI.

The FBI followed up by checking government databases and looking for things such as “derogatory telephone communications, possible use of online sites associated with the promotion of radical activity, associations with other persons of interest, travel history and plans, and education history,” according to FBI Supervisory Agent Jason J. Pack. “The FBI also interviewed Tamerlan Tsarnaev and family members. The FBI did not find any terrorism activity.”

As a result, the bureau concluded he was not a threat. Nonetheless, it added him to a watch list of individuals that are reported as suspicious but have not been directly connected to terrorist groups.

Another step involved creating a record with more biographical information about Tsarnaev, a Green Card holder from Kyrgyzstan who lived in Cambridge, which was added to the FBI’s separate Terrorist Screening Database.

Several months later, the CIA received a similar warning, also from Russia, about Tsarnaev. The CIA then requested that Tsarnaev’s name be put on a different watch list, according to a US intelligence official. That watch list requested officials to keep an eye on him – a so-called “look-out” tag that is not as urgent as the no-fly list barring air travel.

By 2012, Homeland Security reported to one of the central information sharing databases that Tsarnaev had left Boston for Russia in January 2012, but at that point at least one of the watch list tags had expired.

Amidst the questions came a call for caution on fixing blame.

“The press is trying to turn this into another case of 9/11 where we didn’t connect the dots,” said John Hamre, former deputy secretary of defense. “I am not sure it is analogous.”

A spokesman at the Russian Embassy in Washington did not respond to requests for comment.

“I have concerns about what agencies knew what — and the fact that it wasn’t shared,” House Speaker John Boehner said at a press conference. “You know, if the information is good enough for one agency of the government, why shouldn’t it be appropriate for other agencies of the government? We’re going to get to the bottom of it.”

Matt Viser of the Globe staff and Globe Correspondent Julia Edwards contributed to this report. Bryan Bender can be reached at bender@globe.com.